# -*- coding: utf-8 -*-
"""
Action 工厂注册表
─────────────────────────────────────────────────────────────────
将 ActionType → handler 函数的映射集中管理
支持：
  - 内置 handler 自动注册
  - 运行时动态注册/覆盖 handler
  - 通过 create() 工厂方法快速创建 Action 实例
─────────────────────────────────────────────────────────────────
"""

from __future__ import annotations

import logging
import threading
from typing import Callable, Dict, List, Optional, Union

from uas.action.action_model import Action, make_action
from uas.action.action_type import ActionType

logger = logging.getLogger(__name__)


class ActionFactory:
    """
    Action 工厂（单例）
    ─────────────────────────────────────────────────────────────
    使用方式：
        factory = ActionFactory.instance()

        # 注册自定义 handler
        factory.register(ActionType.CAPTURE_PHOTO, my_photo_handler)

        # 创建 Action 实例（自动绑定 handler）
        action = factory.create(
            ActionType.CAPTURE_PHOTO,
            source     = "camera-01",
            resolution = "4K",
            format     = "jpg",
        )
    ─────────────────────────────────────────────────────────────
    """

    _instance = None
    _lock     = threading.Lock()

    @classmethod
    def instance(cls) -> "ActionFactory":
        if cls._instance is None:
            cls._instance = cls()
        return cls._instance

    def __init__(self):
        # { type_key: handler_fn }
        self._handlers: Dict[str, Callable] = {}
        self._init_builtin()

    def _init_builtin(self):
        """自动注册所有内置 handler"""
        from uas.action.actions.builtin_actions import BUILTIN_HANDLERS
        for action_type, handler in BUILTIN_HANDLERS.items():
            self.register(action_type, handler)
        logger.info(f"✅ ActionFactory 初始化，内置 handler={len(self._handlers)}")

    # ── 注册 ──────────────────────────────────────────────────────

    def register(
        self,
        action_type: Union[ActionType, str],
        handler:     Callable,
        override:    bool = True,
    ) -> None:
        """
        注册 Action 处理函数
        :param action_type: ActionType 枚举 或 自定义字符串
        :param handler:     fn(action: Action, ctx: ActionContext) -> Any
        :param override:    True=允许覆盖已有 handler
        """
        key = action_type.value if isinstance(action_type, ActionType) else str(action_type)
        with self._lock:
            if key in self._handlers and not override:
                logger.warning(f"handler 已存在且 override=False，跳过: {key}")
                return
            self._handlers[key] = handler
        logger.info(f"注册 handler: {key} -> {handler.__name__}")

    def unregister(self, action_type: Union[ActionType, str]) -> bool:
        """注销 handler"""
        key = action_type.value if isinstance(action_type, ActionType) else str(action_type)
        with self._lock:
            if key in self._handlers:
                del self._handlers[key]
                logger.info(f"注销 handler: {key}")
                return True
        return False

    def get_handler(self, action_type: Union[ActionType, str]) -> Optional[Callable]:
        """获取指定类型的 handler"""
        key = action_type.value if isinstance(action_type, ActionType) else str(action_type)
        return self._handlers.get(key)

    def has_handler(self, action_type: Union[ActionType, str]) -> bool:
        key = action_type.value if isinstance(action_type, ActionType) else str(action_type)
        return key in self._handlers

    def registered_types(self) -> List[str]:
        return list(self._handlers.keys())

    # ── 工厂创建 ──────────────────────────────────────────────────

    def create(
        self,
        action_type: Union[ActionType, str],
        source:      str = "system",
        priority:    int = 0,
        handler:     Optional[Callable] = None,
        **params
    ) -> Action:
        """
        工厂方法：创建并自动绑定 handler 的 Action 实例
        :param action_type: 行为类型
        :param source:      触发来源
        :param priority:    执行优先级
        :param handler:     若指定则覆盖注册表中的 handler
        :param params:      传递给 Action 的业务参数
        :return:            Action 实例
        """
        resolved_handler = handler or self.get_handler(action_type)
        if resolved_handler is None:
            logger.warning(f"未找到 handler: {action_type}，将使用空处理器")
            resolved_handler = _noop_handler

        action = make_action(
            action_type = action_type,
            handler     = resolved_handler,
            source      = source,
            priority    = priority,
            **params,
        )
        logger.debug(f"创建 Action: {action}")
        return action

    def create_batch(self, specs: List[dict]) -> List[Action]:
        """
        批量创建 Action
        :param specs: [{"action_type": ..., "source": ..., **params}, ...]
        """
        return [self.create(**spec) for spec in specs]


def _noop_handler(action, ctx):
    """空处理器（未注册 handler 时的占位）"""
    logger.warning(f"[noop] Action [{action.type_key}] 无处理器，跳过执行")
    return None


# 全局工厂实例
action_factory = ActionFactory.instance()